Safety clamp



NOV. 10, 1942. G, D JQHNSON 2,301,625

SAFETY CLAMP Filed April 9, 1941 2 Sheets-Sheet l 4 /0 dife J/ fue w29/J 55 l' Il x l JG l l i, JL, [L J4 44 x; l 4@ l 34 K" Nov. 10, 1942. Q D JOHNSON 2,301,625

SAFETY'CLAMP Filed April 9, 1941 2 Sheets-Sheet 2 Patented Nov. 10, 1942 UNITED spares.

SAFETY CLAMP Application April-9, i941, SerialNo. 387,563v

11 Claims. (Ol. 2li- 263) This` invention has to do with Well drillingtools and" has particular reference to safety clamps for preventing the droppingand loss ofslips may` allow'the pipe, liner or other objectY to fall into the Well, necessitating an expensive, time consuming shing operation for its` recovery;

Another object of this inventionI istoprovideV a safety clamp that maybe quickly engaged aboutthe pipe, drillcollar or otherobject, at a point above the rotary table andfthat is adapted to engage downagainst theslipsor other parts` at' the rotary table to prevent the falling and loss ofthe pipe or object in the event the rotary table slips fail to support the pipe-or object.

Anotherobject of this invention is'to provide a safety clamp-of the character reerredto that is operable to obtain a dependable, positive gripV on the pipe,- drillfcollar, liner, or the like, even when the latter presents-a smooth surface devoidof` shoulders, collars and recesses.

Another object of thisinvention is to provide a safety clamp'of the character referred to .that

accurately conforms-t0 the pipe, drilll collaror` other object, serving to'grip the object at closely spaced points throughout' its circumference even though the object may be out of round.

Another and important object ofthe invention is'to provide a` safety clamp of the character mentioned that may be easily and quickly adjusted in effective diameter throughout a substantial range'to adapt it for useon pipe, and the like, through `a Wide range. of' sizes A further object of this inventionis toprovide a safety clamp Whichembodies a minimum number of simple sturdy parts.

The various objects and features of my invention will be fully understood `from theV following detailed description of the invention,

throughout which description reference is-made to the accompanying drawings, in which:

' Fig. 1 is a plan vieW'of the safetyclamp of this inventionI engaged about a drill pipe, or like object, showing the objectV in horizontal cross4 signedlto Vreceive and mount the slipsgl I.

section. Figi 2 is la side elevation-,of the clamp and a portion of the object showing the clamp spaced above the slips of the rotary table. Fig. 3 is an enlarged vertical detailedsectional View taken through one of the intermediate linksI and a handle. shovvingthe link slip engaged with the pipe or object. Fig. 4 is a plan View of one of the intermediateilink assemblies. Fig. 5 is a View of the inner` side cfone of the intermediate link assemblies. Fig,` Gis a perspective View of oneofthe intermediate links andFig. 7 'is a reduced plan View illustrating the clamp .engaged about a largerobject.

The safety clamp of the, present .invention may i be said to comprise, generally, a pluralityv of pivotally connected links forming alinkassembly Iii, slips II carriedby the linksv for gripping the pipe or object O, and releasableimeansY I?!A forl connecting the ends of` the. link assembly, Ito holditv engaged about the `object O.

The link assembly IG, When itsv ends are. connected by the means I2, forms a, substantially annular structure for tting about thepipe or object O. and, in accordance with the invention, may be readily varied asto its length or diameter to tpipe and like objectsvarying greatly in diameter. rality of intermediate links I3, a right end link I4 and a left end link I5. The intermediate links i3 are preferably identical and the number ernployed depends upon the size of the pipe being handled. One end of each intermediate link I3 has a horizontally projecting lug or eye I6 provided With afvertical opening Il. The other. end` of` each intermediate. link I3has a horizontally projecting fork or yoke I8 ,comprising vertically spaced earsor lugs. The yokes I8 are adapted to receive the eyes I6 of adjacent links I3 and havevertical openings, I9 for registering with the` opening I1 of the eyes. Hinge pins 20 are passed through the openings I land` I9 of the fitted together eyes and yokes to releasably pivotally connect the linksY I3. The upper ends of` theY pins 23 have heads 2-I` which prevent downward movement of the pins andfcotter. keys 22 are passed through openings in the lower portions. of the pins to preventupvvard` movement and displacement. Each tongue or eyel I6 has-a stop 22a projecting from its periphery or edgevfor cooperating with the adjacent link. I3 to limit the relative outwardv pivoting of the links. As illustrated, the` eyes I6 and yokes IB arev quite thick and heavy to have the required strength.

The links `I3 have intermediate portions 23de- The The assembly It) comprises a plu-` intermediate portions 23 project inwardly at the inner sides of the links I3 and are in the form of upright, generally cylindrical, hubs or bosses. The inner sides of the portions 23 have vertical guide ways 24. There is preferably a single guide way 24 in each link I3. The side walls of the guide ways 24 are straight and parallel, while the rear walls 25 are flat and slope downwardly and inwardly relative to the central vertical axis of the link assembly and object O. Flat walled grooves 25 occur in the side Walls of the guide ways 24 where they join the rear walls 25. The grooves 2E slope downwardly and inwardly and are open at the tops of the portions 23.. tical slots or recesses 21 are provided in the sloping rear walls 25. The recesses 21 extend downwardly from the tops of the portions 23 and terminate before reaching the lower ends of the portions. As best illustrated in Figs. 3 and 6, the recesses 21 are graduated or stepped, that is, they are deeper at their upper portions to leave or provide upwardly facing shoulders 23 spaced above their lower ends.

The end links I4 and I5 occur at the ends of the link assembly I and are formed to receive and carry cooperating elements of the means I2. The end link I4 is similar, generally, to the intermediate links I3 being provided at one end with a fork or yoke 29 for receiving the eye I 6 of the adjacent link I3 and provided with a vertical opening for receiving a hinge pin 20. The link I4 includes a body portion 23 provided with a guide way 25 having grooves 26 and a recess 21 as found in the intermediate links I3. The free or outer end of the link I4 has a pair of Vertically spaced lugs 30. The lugs 39 have vertical openings 3| and are spaced apart vertically a substantial distance. The left end link I5 is provided at its inner end with a tongue or eye I5 received in the yoke I8 of the adjacent link I3 and is pivotally connected with the link I3 by a hinge pin 20 passed through the openings of the yoke and eye. The inner side of the link I5 has a portion 23 provided with thek guide way 25, the grooves 26 and the recess 21 as found in the other links of the assembly. The free or outer end of the link I5 has a pair of vertically spaced lugs 32 similar to the lugs 3| and provided with vertical openings 33.

The link assembly I II is preferably provided with handles to facilitate the handling and manipulation of the safety clamp. In the construction illustrated there are two like handles each having a channel 34 freely fitting about the eX- terior of the assembly I i) and arranged so that its anges engage the upper and lower sides of the assembly. 'I'he flanges of the channels 34 have openings for registering with the openings I9 of the links I3 and adapted to receive the hinge pins 20. Thus, the hinge pins 20 serve to secure the handles to the assembly I5. Suitable handle grips 35 extend outwardly from the channels 34. It is to be observed that the handles just described do not require the employment of special links or of special means of attachment.

The slips II are carried by the several links of the assembly II) and are operable to grip the object O to stop or prevent downward movement of the object through the clamp. There is `a slip II carried by each link I3, I4 and I5 and the several slips are preferably identical. The gripping slips I I are vertical elongated wedge parts operating in the guide ways 24 of the links. The opposite sides of the slips II are flat and vertical to ride on the side walls of the guide ways Ver- 24 and the rear surfaces of the slips are at and are pitched downwardly and inwardly to slidably bear on the walls 24. The opposite sides or edges of the slips II have longitudinal ribs or keys 35 slidably tting the grooves 25. The keys 36 guide the slips II and hold them in engagement with the sloping walls 25. The exposed or active faces of the slips II are substantially vertical and are slightly concave to generally correspond to the curvature of the object O. Wickers or teeth 31 are provided on the active faces of the slips II. The teeth 31 slope or face upwardly and inwardly to eiectively and dependably grip the object O when the same tends to move downwardly through the clamp. In the embodiment of the invention disclosed there are two vertical rows of teeth 31 on each slip.

In accordance with the invention the slips II are spring held or spring urged being yieldingly held in raised positions where they have only initial cooperation with the object O. Fingers 38 project horizontally from the backs of the slips II and are received in the deepened upper portions of the recesses 21. The bodies of the slips II4 may be cut away below the fingers 38 to increase the extent of the lower sides of the fingers. It is preferred to cut away the slip bodies to leave or provide vertical grooves 39 in the backs of the slips which register with the recesses 21. Cotter keys 4I) are passed outwardly through horizontal openings 4I in the rear walls of the portions 23 and are engageable by the fingers 33 to limit the upward movement of the slips I I. Coiled springs 42 are arranged under compression between the lower walls of the recesses 21 and the under sides of the lingers 38 to urge the slips I I upwardly. The springs 42 initially or normally hold the slips II in their raised positions where the lingers 38' engage against the cotter keys 4I) and the springs are yieldable to permit substantial downward movement of the slips relative'to their links I3, I4 and I5. The recesses 21 and the grooves 39 guide and retain the vertically disposed springs 42.

The parts are formed and related so that the slips II project from the inner sides of their respective links I3, I4 and I5 to engage or grip the object O when in their uppermost positions with their iingers 38 engaged against the keys 40. The ngers 38 have substantial vertical movement in the recesses 21 whereby the slips I I may have initial cooperation with objects Ovarying one inch or more in external diameter without the addition or removal of links of the assembly lil. The initial engagement of the slips I I with the smaller objects O within such a range (one inch or more), may hold the slips in positions where their iingers 38 are slightly below the cotter keys 40.

The means I2 may be easily and quickly operated to connect the ends of the link assembly I3 to have the assembly engage about the object O so that the slips I I obtain an initial gripping en gagement with the object. The means I2 includes a pivot block 43 pivotally secured between the lugs 32 of the link I5 and a screw 44 carried by the link I3 and passing through the block. Pins or screws 45 are engaged or passed through the openings of the lugs 32 and are threaded in openings 45a in the upper and lower ends of the block 43 to retain the block for pivoting about a vertical axis. The block 43 has a horizontal openingv 45 freely passing the screw 44. The screw '44 is adapted to be releasably connected with the end link I4. An eye 41 is formed on the inner end of the screw 44 and is adapted to be inserted between the lugs 3|).` Theeye4l'. has a. i

vertical opening 48 adapted to be brought into registration with the openings 3| and a pin 49is` passed through the openings 3| and 43 to pivotally secure the pin 44 to the link I4. A head 5I] on the upper end of the pin 49prevents displacement of the pin.

The screw 44 passes through the opening 45 of the block 43 with suitable clearance and eX- tends a considerable distance beyond the block. A nut 5| is threaded on the projecting portion of the screw 44 and is adapted to react against the pivot block 43 to draw the assembly I3 about the object O.v The nut 5| is provided with a polygonal portion 52l readily engageable by a wrench or the like. Prior to the assembling of the clamp about the object O the screw 444v is carried by the'block 43 and is free of: the link I4. The eye 4l and the nut` 5| prevent detachment of the screw fromthe block43. When the clamp has been assembled' about the object O the eye 41 of the screw'is entered between the lugs 3E! and the pin 49 is passed through the openings 3| and 48 to connect the opposite ends of the assembly ID.. The nut` 5i is then threaded inwardly against the block 4?.` to tighten the assembly IU to the desired degree.

In accordance with the invention the-links I3 are proportionedso that the addition or removal of a link |3 produces a known or definite change in the effective gripping-diameter of the clamp. For example, the links I3 or certain` of them, may be proportioned so that the addition of one link I3A will increase the effective' gripping diameter of thei-clamplonel inch and'conversely 'the 3% inches to i5/3l inches -in external diameter, thev embodiment of a total` number of eight links adapts the clamp to grip pipe ranging from 41/2 to 5%- inches in external diameter, the embodiment of a total number of nine links adapts the clamp to-grip pipe ranging from 51/2 to 6%,inches in external diameter, the embodiment of av total number of ten links adapts the clamp to handle' pipe ranging from 61/2 to "I5/8 inches in external diameter, and so on to handle the largest ofthe pipe that may be used;`

Fig. 1 of the drawings shows the clamp equipped with a total number ofi nine links I3", I4 and |5 for engaging a medium size: pipe or object O,v

while Fig. 7 shows the clamp provided with a total of thirteenv links for gripping a larger object O. The construction is such that links I3 may be easily and quickly added to and removed from the assembly. One of the end links, say the link I4, is quickly disconnected from the assembly by removing the hinge pin 20 at its inner end and this exposes the end of the assembly of intermediate links |3 for the removal or addition of links as may be required. Additional links may be quickly secured to the assembly by means of the hinge pins 2Q and the hinge pins are readily removed to permit the disconnection of links. Each link I3 is a complete unit equipped with a slip II and the adjustment of the clamp for the gripping of objects of.' ycliierent sizes requires merely the addition or removal of these coinplete assemblies. The safety clamp may be delivered or supplied to the well with a full set of links I3 so that the safety clamp will be available for use on pipe, liners, ldrill collars, etc., of all sizes.

In employing the safety clamp the assembly I0 is'provi'ded with the correct total number of links I3, I4 and l5 to adapt it for gripping the particular pipe, liner, or other object O being handled at the derri'ck, The assembly I!! is then engaged about the object O a short distance above the rotary table T and its end links I4 and |5 are connected by the means I2 as described above. Fig. 2 of the drawings shows the safety clamp engaged about the object O above the rotary table T. The nut 5I is given a few turns to tighten the assembly` I0 about the object. The engagement of the slips with the object O will hold the safety clamp against movement along the object. In the event the rotary table slips S, or other pipe gripping means of the drilling rig, fail when making up or disconnecting the drilling string, the object O may start to fall into the well. The safety clamp engaged about the object O moves downwardly with the object until itl strikes the slips S or other part at the table T. When the safety clamp comes to rest against the slips S of the table T its downward movement is stopped and the object O tends to move do-wnwardly through the safety clamp. The spring held slips I| engaged with the object O ride downwardly on the walls 25 and are thus forced into tighter engagement with the object. The slips II are very securely and dependently engaged with the object O by the downward movement of the object or by the weight of the object, or both, and positively prevent the object from falling into the well. With the pipe or object O stopped and held by the safety clamp suitable steps may be taken to reengage the object and raise it for further operations.

Having described only a typical preferred form and application of my invention, I do not wish to be limited or restricted to the specio details herein set forth, but wish to reserve to myself any variations or modiiications that may appear to those skilled in the art or fall within the scope of the following claims.

Having described my invention, I claim:

l. A clamp of the character described comprising a multiplicity of like intermediate links, two end links, means for pivotally connecting the links to form a continuous assembly with the end links at the ends of the assembly, means on the end links for connecting the ends of the assembly whereby the assembly may be arranged around a pipe or like object, and shiftable slips carried by each link for gripping the object.

2. A clamp of the character described comprising a multiplicity of like intermediate links, two end links, means for pivotally connecting the links to form a continuous assembly with the end links at the ends of the assembly, means on the end links for connecting the ends of the assembly whereby the assembly may be arranged around a pipe or like object, a shiftable gripping slip for each link, and spring means for supporting the slips on their links.

3. A clamp of the character described comprising a multiplicity of identical links pivotally connected to form an assembly adapted to be arranged around a pipe or like object, means at the ends of the assembly for joining said ends to hold the assembly around the object, at least one of said means being detachable from the link assembly, and a spring loaded slip on each link for gripping the object 4. A clamp of the character described comprising a multiplicity of identical links pivotally connected to form an assembly adapted tol be arranged around a pipe or like object, means at the ends of the assembly for joining said ends to hold the assembly around the object, at least one of said means being detachable from the link assembly whereby the number of said links may be easily changed to adapt the essembly for engaging around objects of different diameter, and a slip carried by each link for gripping the object.

5. A clamp of the character described comprising a plurality of links, means for detachably pivotally connecting the links to form an assembly adapted to be engaged around objects, each link being proportioned to add approximately one inch to the eifective gripping diameter of the assembly, object gripping slips on the links, and means for connecting the ends of the assembly.

6. A clamp of the character described comprising a plurality of links, means for detachably pivotaily connecting the links to form an assembly adapted to be engaged around objects, each link being proportioned to increase the effective diameter of the assembly a given amount, a gripping slip shiftable vertically on each link and movable inwardly upon downward shifting, spring means urging the slips upwardly, and means for releasably connecting the ends of the assembly.

7. A clamp of the character described comprising a plurality of links, means for detachably pivotally connecting the links to form an assembly adapted to be engaged around objects, each link being proportioned to increase the effective diameter of the assembly a given amount whereby the clamp may be used on objects of larger and smaller diameter by increasing or decreasing the number of links in said assembly, a gripping slip shiftably vertically on each link, and movable inwardly upon downward shifting, spring means urging the slips upwardly, and

rmeans for releasably connecting the ends of the assembly to hold the slips in initial gripping engagement with the object including a member cletachably secured to one end of the assembly, a member on the other end of the assembly, and a screw threaded part on one member cooperable with the other member.

8. A clamp of the character described ccming the number of links in said assembly, a gripping slip shiftably vertically on each link, and movable inwardly upon downward shifting, spring means urging the slips upwardly, and means for releasably connecting the ends of the assembly to hold the slips in initial gripping engagement with the object including a member detachably secured to one end of the assembly,

a member on the other end of the assembly, aY

screw shiftably carried by one of said members, means for detachably connecting the screw with the other member, and a nut on the screw for tightening the assembly about the object.

9. A clamp of the character described comprising a multiplicity of like intermediate links, two end links, means for pivotally connecting the links to form a continuous assembly with the end links at the ends of the assembly, each link having a guideway with a sloping wall, slips in the guideways forced inwardly against the object through cooperation with the sloping walls upon downward movement, springs for urging the slips upwardly, and means on the end links for releasably connecting the ends of the assembly and operable to tighten the assembly about the object so that the slips obtain initial engagement with the object.

10. A clamp of the character described comprising a multiplicity of like intermediate links, two end links, means for pivotally connecting the links to form a continuous assembly with the end links at the ends of the assembly, each link having a guideway with a sloping wall andV a. recess, slips in the guideways forced inwardly against the object through contact with said walls upon downward movement, Iingers on the slips entering the recesses, springs in the recesses acting on the lingers to urge the slips upwardly, and means on the end links for releasably connec-ting the ends of the assembly and operable to tighten the assembly onto the object so that the slips have initial cooperation with the object.

11. A clamp of the character described comprising a multiplicity of like intermediate links,

7 two end links, means for pivotally connecting the links to form a continuous assembly with the end links at the ends of the assembly, each link having a guideway with a sloping wall and a recess, slips in the guideways forced inwardly against the object through contact with said walls upon downward movement, fingers on the slips entering the recesses, springs in the recesses acting on the fingers to urge the slips upwardly, keys on the links engaged by the fingers to limit the upward movement of the slips and removable to allow removal of the slips, and means on the end links for releasably connecting the ends of the assembly and operable to tighten the assembly onto the object so that the slips have initial cooperation with the object.

Y GLENN D. JOHNSON. 

